A typical communication system includes a plurality of access networks each configured to provide client devices with connectivity to various transport networks and service platforms. These access networks may serve client devices over wired and/or wireless channels, to facilitate circuit-switched and/or packet-switched communication of various forms. By way of example, a communication system may include multiple radio access networks (RANs) each configured to provide wireless communication devices (WCDs), such as cell phones or other wirelessly-equipped devices, with connectivity to one or more transport networks such as the public switched telephone network (PSTN) and/or the Internet for instance, and to provide WCDs with connectivity to one or more telephony and messaging service platforms.
A representative communication system, for instance, may include two access networks, one that functions primarily to provide client devices with access to engage in packet-switched communications such as Internet Protocol (IP) based communications, and another that functions primarily to provide client devices with access to engage in circuit-switched communications such as legacy voice calling services. For example, the first access network may be a Long Term Evolution (LTE) network, which functions primarily to provide WCDs with access to engage in high speed packet-data communications, and the second access network may be a legacy Code Division Multiple Access (CDMA) or Global System for Mobile Communications (GSM) network, which functions primarily to provide WCDs with access to engage in voice calls. Other examples are possible as well.
In such an arrangement, both access networks may connect with a common media system that is configured to handle message communication, such as Short Message Service (SMS) communication, to and from served devices. For instance, both access networks may connect with an IP multimedia subsystem (IMS), and the IMS may include an SMS gateway that is configured to receive, store, and forward SMS messages to WCDs served by either access network. In practice, the SMS gateway could be configured to use different types of routing mechanisms for transmitting SMS messages to WCDs via the different access networks. For example, the SMS gateway could be configured to use the well-known Session Initiation Protocol (SIP) for routing SMS messages to WCDs via access networks that provide WCDs with packet-switched communication service, and the SMS gateway could be configured to use the well-known IS-41 signaling protocol for routing SMS messages to WCDs via other, legacy access networks.